Spa Pools – Risk & Relaxation

Spa Pools – Risk & Relaxation

11th January 2018

Spa pools used to be something of a rarity, but in recent years have become quite commonplace, particularly in hotels, leisure centres and homes across the UK.

These types of pool have a number of requirements for safe operation, every owner and operator should be made aware of this guidance and take steps to prevent potential outbreaks or Legionnaires’ disease.

Foreseeable Risks

Spa pools have a number of reasonably foreseeable risks attributed to their environmental conditions, it’s these conditions that have the potential to facilitate and encourage the growth of Legionella.

These factors need to be taken into consideration when assessing all water systems, which includes spa pools. The common factors are:

  • Water that is stored or recirculated
  • Temperatures within the system are between 20°C – 45°C
  • There is the potential for microbial growth within the system
  • Water is dispersed as an aerosol
  • A means of exposure to contaminated aerosols

Spa pools naturally fall victim to a couple of risk factors simply by design.

They usually hold a body of water that is used by multiple people before it is changed and is exposed to a high volume of organic material. While in use, the water is manipulated in such a way that aerosols are produced in vast quantities.

While any pool has the potential to be used commercially or privately, commercial pools tend to have a larger capacity for occupants and require more stringent control measures.

The ideal temperatures for controlling Legionella, namely ≤20°C for cold water and ≥60°C for hot, might not be suitable for an enjoyable spa experience.

Managing the Risk

It may seem like these items are ticking bombs waiting for the right moment to go off, but a few simple steps can make all the difference when it comes to safety.

When it comes to personal use only, there’s little to do outside of the manufacturer’s guidelines for maintenance. While actual requirements will vary depending on the characteristics of the pool, but a few things that are pretty much universal:

  • pH should be kept between 7.2 – 7.6
  • Chlorine levels should be between 3.0 – 5.0 PPM*
  • Alternatively, Bromine levels should be between 4.0 – 6.0 PPM*

*Parts per million

It’s recommended that regular water analysis be carried out to help monitor the quality of the water in use and the pool be drained and filled with fresh water.

Commercial style pools have additional requirements in order to be considered compliant with the few pieces of legislation that cover them.

The first step is to carry out a risk assessment on the pool, this will form the basis of an effective scheme of control measures. The assessment will also serve as evidence that the relevant factors and preventative steps have been considered.

The risk assessment must take into consideration a number of factors, including:

  • Water supply – quality and source
  • Water system including schematic diagram and construction materials
  • Potential sources of contamination
  • Operational risks, procedures & controls
  • Management responsibilities & competency/training of key personnel
  • Inspection and maintenance schedules and processes
  • Potential remedial actions
  • Capacity to review the assessment as necessary

There are a number of options to treat spa pools, but among the most common are chlorine and bromine.

If there are 5 or more employees, records of the risk assessment, monitoring and tests/samples must be kept. These records must contain accurate information (including who carried out the work and when) and must be signed or authenticated to be considered valid.

Avoidable Outbreaks

Despite there being a number of resources, advice and guidance available, there have been a number of unfortunate Legionella outbreaks caused by hot tubs.

A quite notable case within recent years involves a pool that had never actually been used. A DIY warehouse store had a pool on display, set up to showcase the features of the product and was effectively left to run.

It is believed that the pool was left exposed to the environment and the water wasn’t changed or treated. This combined with the operating temperature and ample aerosol production, provided the perfect opportunity for Legionella to not only grow but disperse into the air.

This led to 21 people within the local area contracting the disease, 2 of which died from the disease. The company has been fined £1 million and paid our a further £200,000 to the families of the affected.

A more recent incident occurred just last year, over a period of a few weeks there were 27 cases of Legionnaires’ disease which have since been attributed to an exterior hotel jacuzzi.

Although there are risks associated with spa pools and hot tubs, they are easy enough to handle and shouldn’t pose too much of a problem.

The main thing to remember is to stay on top of the appropriate control measures and make sure effective safety measures are in place.

By Simon Stone

Nant Ltd

The Development Centre,
Wolverhampton Science Park,
Glaisher Drive,
West Midlands
WV10 9RT


01902 636355